JPH1155807A - Brake controlling device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform smooth braking operation and secure good brake feeling even if the voltage of a battery exceeds a given upper limit in a brake controlling device for an electric vehicle. SOLUTION: If the voltage of a battery 13 detected by a voltage detecting means exceeds a given upper limit while regenerative braking by motor controlling means 10a, etc., is in operation, regenerative braking torque by a motor controlling means 10a, etc., is reduced with a given cycle. When the increasing trend of the reduced amount for each given cycle starts reversing, the state of the reduced amount is held. Then, until the vehicle stops even after the increasing trend of the reduce amount for each given cycle started reversing, braking is controlled in such a way that hydraulic pressure braking is continued by a hydraulic pressure controlling means 10b, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for an electric vehicle that uses both regenerative braking and hydraulic braking, and more particularly, to regenerative braking for battery protection when the battery voltage exceeds a predetermined upper limit. The present invention relates to a braking control device that suppresses the pressure and compensates for this shortage by hydraulic braking.

[0002]

2. Description of the Related Art In recent years, in an electric vehicle using an electric motor as a drive source, regenerative braking is performed in which the electric motor functions as a generator and charges a battery to recover energy and increase energy when the electric motor is driven. Is being done. Since there is a limit to the application of the braking force by the regenerative braking, it is necessary to compensate by the hydraulic braking. For example, as in the braking device for an electric vehicle described in Japanese Patent Application Laid-Open No. 5-161210, the hydraulic braking and the regenerative braking are performed. Are used together.

[0003]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 5-161 is disclosed.
In a conventional electric vehicle braking control apparatus as disclosed in Japanese Patent Publication No. 210-210, if the battery voltage rises during a regenerative braking operation and exceeds a predetermined threshold, the regenerative braking torque is suppressed to protect the battery. And the braking force due to regenerative braking is controlled to decrease. However, the decrease in the regenerative braking torque at this time is temporary, and the regenerative braking operation is restored when the voltage of the battery decreases and the regenerative braking becomes possible. In this case, since the other braking force that was compensated for when the regenerative braking torque was reduced, for example, the braking force due to hydraulic braking remains, the deceleration of the vehicle increases as much as the regenerative braking operation is restored. Become. Therefore, the braking force is applied against the driver's intention, which is not preferable in terms of brake feeling.

Accordingly, the present invention relates to a braking control device for an electric vehicle that uses both regenerative braking and hydraulic braking, so that even when the battery voltage exceeds a predetermined upper limit, the braking operation is performed smoothly until the vehicle stops. And to secure a good brake feeling.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electric motor connected to wheels of a vehicle, a battery mounted on the vehicle, and a rotary drive of the electric motor using the battery as a power source. A motor control means for applying a driving force to the wheel and applying a braking force to the wheel by regenerative braking of the electric motor; and a brake fluid for a wheel cylinder mounted on the wheel in response to an operation of a brake operation member. In a braking control device for an electric vehicle, comprising: a hydraulic pressure control unit that applies a braking force to the wheel by hydraulic braking that supplies pressure; a voltage detection unit that detects a voltage of the battery; When the voltage of the battery detected by the voltage detecting means exceeds a predetermined upper limit during the braking operation, the regenerative braking torque by the motor control means is increased at a predetermined cycle. A reduction means for reducing, and a holding means for holding a state of the reduction amount when the reduction amount in the predetermined cycle at which the reduction means decreases from an increase to a decrease is provided, wherein the reduction means reduces the reduction amount. Even after the amount of reduction in the predetermined cycle has changed from increasing to decreasing, control is performed so that hydraulic braking by the hydraulic pressure control means is continued until the vehicle stops.

In the above-mentioned brake control device, the hydraulic pressure control means includes a static hydraulic pressure output means for increasing a brake fluid in a reservoir in response to an operation of the brake operating member and outputting a static hydraulic pressure; An auxiliary hydraulic pressure source that boosts the brake fluid and outputs power hydraulic pressure independently of the operation of the brake operating member, and adjusts the output power hydraulic pressure of the auxiliary hydraulic pressure source in accordance with the operation of the brake operating member. A dynamic hydraulic pressure output means for outputting a dynamic hydraulic pressure, and supplying an output hydraulic pressure of the dynamic hydraulic pressure output means to a wheel cylinder mounted on a wheel connected to the electric motor to perform hydraulic braking. And the hydraulic braking by the output hydraulic pressure of the dynamic hydraulic pressure output means is continued until the vehicle stops even after the reduction amount in the predetermined cycle, which is reduced by the reduction means, changes from increasing to decreasing. Control to It may be and.

The dynamic hydraulic pressure output means receives the output hydraulic pressure of the auxiliary hydraulic pressure source, and uses the output hydraulic pressure of the master cylinder as the static hydraulic pressure output means as the pilot pressure. A regulator that regulates and outputs a hydraulic pressure, or a hydraulic booster that regulates a boost hydraulic pressure (regulator hydraulic pressure) and drives the master cylinder in a similar manner can be used.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a braking control device for an electric vehicle according to an embodiment of the present invention, which includes an electric motor 11 for performing regenerative braking and a hydraulic pressure control device for performing hydraulic braking. A master cylinder 2 as a means,
The regulator 3 as the dynamic hydraulic pressure output means is configured to be driven according to the operation of the brake pedal 5. In FIG. 1, wheels FR indicate front right wheels as viewed from a driver's seat, wheels FL indicate front left wheels, wheels RR indicate rear right wheels, and wheels RL indicate rear left wheels.
Wheel cylinders 51 to 5 are provided for R, FL, RR, and RL.
4 is attached. In the present embodiment, a so-called front-rear piping type brake hydraulic system divided into a front-wheel hydraulic control system and a rear-wheel hydraulic control system is configured.

The electric vehicle according to the present embodiment has a front wheel F
R and FL are drive wheels, and rear wheels RR and RL are related to so-called front wheel drive of driven wheels. The wheels FR and FL are connected to a drive electric motor 11 via a transmission 12. The drive is controlled by the electronic control unit 10. The electronic control unit 10 includes a microcomputer 10a for motor control as motor control means for driving and controlling the electric motor 11 and a microcomputer 10b for hydraulic pressure control as hydraulic pressure control means. The detailed configuration is the same as that described in, for example, Japanese Patent Application Laid-Open No. 7-336806, and a description thereof will be omitted.

The electric motor 11 generates a rotating magnetic field by applying AC power to three-phase windings of the stator,
It is composed of an induction motor that rotationally drives a rotor having a permanent magnet. Therefore, an inverter (not shown) is provided in a motor drive circuit (not shown) controlled by the microcomputer 10a. According to the electric motor 11, when the wheels FR and FL are rotating,
By generating a magnetic field in the direction in which the rotation is stopped by the stator, a braking force can be applied to the rotor, and the electromotive force generated in the windings of the stator can be recovered by the battery 13. Thereby, regenerative braking is performed.

In FIG. 1, the pressure chamber of the master cylinder 2 is connected to a low-pressure reservoir 4,
A hydraulic pressure limit switching device 20 for adding and switching hydraulic braking to regenerative braking is provided in the main hydraulic passage 8 on the front wheel side connecting the pressure chambers of the vehicle and the wheel cylinders 51 and 52 in front of the vehicle.
Is interposed. On the other hand, a hydraulic pressure limiting switching device 30 is interposed in the main hydraulic pressure passage 9 on the rear wheel side that connects the regulator 3 and each of the wheel cylinders 53 and 54 behind the vehicle. The configuration is slightly different from the switching device 20.

An auxiliary hydraulic pressure source 40 is connected to the regulator 3, and these are connected to the low-pressure reservoir 4 together with the master cylinder 2. The auxiliary hydraulic pressure source 40 has a hydraulic pump 41 and an accumulator 44. Hydraulic pump 4
1 is driven by an electric motor 42 and has a low-pressure reservoir 4
, And the brake fluid is supplied to the accumulator 44 via the check valve 43 and accumulated.

The electric motor 42 is driven in response to the hydraulic pressure in the accumulator 44 falling below a predetermined lower limit, and stops in response to the hydraulic pressure in the accumulator 44 exceeding a predetermined upper limit. . Thus, a so-called power hydraulic pressure is supplied from the accumulator 44 to the regulator 3 as appropriate. The regulator 3 receives the output hydraulic pressure of the auxiliary hydraulic pressure source 40 and uses the output hydraulic pressure of the master cylinder 2 as a pilot pressure to regulate the pilot hydraulic pressure to a proportional regulator hydraulic pressure (a value substantially equal to the master cylinder hydraulic pressure). Since the basic configuration is well known, the description is omitted. A part of the regulator hydraulic pressure is used for boosting the master cylinder 2.

As shown in FIG. 1, the hydraulic pressure limit switching device 20 includes a first relief valve 21, an electromagnetic on-off valve 22, a proportioning valve 23, and a second relief valve 2.
6 are connected in parallel, and a second relief valve 26
, An electromagnetic on-off valve 27 is arranged in series. The first relief valve 21 restricts the communication of the main hydraulic pressure passage 8 until the output hydraulic pressure of the master cylinder 2 reaches the predetermined pressure Pc, and connects the main hydraulic pressure passage 8 when the output pressure exceeds the predetermined pressure Pc. Things. Further, the second relief valve 26 restricts the communication of the main hydraulic pressure passage 8 until the output hydraulic pressure of the master cylinder 2 reaches a predetermined pressure Pb lower than the predetermined pressure Pc. The main hydraulic pressure path 8 communicates with the main hydraulic pressure path 8.

The electromagnetic switching valve 22 is driven and controlled by the electronic control unit 10 and opens and closes in accordance with the maximum regenerative braking force. The electromagnetic switching valve 27 is also driven and controlled by the electronic control unit 10 to reduce the maximum regenerative braking torque. The solenoid valve opens and closes according to the speed of the vehicle or the maximum regenerative braking torque of the vehicle. The proportioning valve 23 is a hydraulic pressure control valve that controls the output hydraulic pressure of the master cylinder 2 according to the operation of the brake pedal 5 in a predetermined relationship and supplies the hydraulic pressure to the wheel cylinders 51 and 52. Although it has substantially the same configuration as the proportioning valve used for distribution control, the hydraulic pressure at the turning point is kept low as described later. In addition, the first relief valve 21 (the electromagnetic on-off valve 22)
Pressure sensors 24 and 25 are disposed on the upstream side and the downstream side, respectively.

On the other hand, the hydraulic pressure limit switching device 30 on the rear wheel side
The relief valve 31, the solenoid on-off valve 32 and the proportioning valve 33 are connected in parallel, and the one corresponding to the second relief valve 26 and the solenoid on-off valve 27 is not provided. It may be. The relief valve 31 restricts the communication of the main hydraulic passage 9 until the master cylinder hydraulic pressure reaches the predetermined pressure Pc, and connects the main hydraulic passage 9 when the master cylinder hydraulic pressure becomes equal to or higher than the predetermined pressure Pc. Also, the electromagnetic on-off valve 32 is
The main hydraulic pressure passage 9 is opened and closed according to the regenerative braking torque in the same manner as described above. The proportioning valve 33 has the same function as the proportioning valve 23.

The first relief valve 21, the solenoid on-off valve 22 and the proportioning valve 23 which constitute the above-mentioned hydraulic pressure limit switching device 20 have the characteristics shown in FIG. That is, the characteristics of the proportioning valve 23 are such that the master cylinder hydraulic pressure increases in response to the operation of the brake pedal 5 at the beginning of the braking operation, and the wheel cylinder hydraulic pressure increases in proportion to the master cylinder hydraulic pressure. When the pressure reaches the predetermined pressure Pa, the pressure becomes substantially constant. Even if the master cylinder pressure increases, the wheel cylinder pressure only slightly increases. The predetermined pressure Pa is set to a low value such that the wheel cylinder 51 and the like are filled with brake fluid and a brake pad (not shown) comes into contact with a rotor (not shown). Thus, the proportioning valve 23 has a function of filling the wheel cylinder with the brake fluid at the beginning of the brake operation,
It has a function of shutting off the hydraulic pressure until the first relief valve 21 operates, and a function of returning the brake fluid from the wheel cylinder 51 or the like to the master cylinder 2.

The characteristics of the first relief valve 21 are shown in FIG.
As shown by a two-dot chain line, the master cylinder is closed until the master cylinder pressure reaches the predetermined pressure Pc, opens when the master cylinder pressure exceeds the predetermined pressure Pc, and thereafter, the wheel cylinder pressure is proportional to the increase in the master cylinder pressure. The pressure increases. Further, as shown by the solid line, the characteristic of the second relief valve 26 is a closed state until the master cylinder hydraulic pressure reaches a predetermined pressure Pb (Pb <Pc), and opens when the master cylinder hydraulic pressure exceeds the predetermined pressure Pb. Thereafter, the wheel cylinder pressure increases in proportion to the master cylinder pressure. The solenoid on-off valve 27 is a valve for controlling the operation of the second relief valve 26. The solenoid on-off valve 22 has a wheel whose opening position matches the master cylinder hydraulic pressure as shown by a broken line in FIG. It has the characteristics of cylinder hydraulic pressure. In other words, in FIG. 7, a broken line indicating the characteristics of the electromagnetic on-off valve 22 and the first relief valve 21 or the second
Relief valve 26 and proportioning valve 2
The area surrounded by the solid line showing the characteristic of No. 3 is a pressure reduction area, and is a range in which regenerative braking is performed instead of hydraulic braking.

As shown in FIG. 1, the brake pedal 5 is provided with a brake switch 6 which is turned on when the brake pedal is depressed, and is connected to the electronic control unit 10 like the pressure sensors 24 and 25. . Also, the shift position of the transmission 12 is detected and the electronic control unit 10
Is supplied with a detection signal. Further, wheels FR, FL, R
Wheel speed sensors 91 to 94 are provided for R and RL,
These are connected to the electronic control unit 10, and the rotation speed of each wheel, that is, a pulse signal having a pulse number proportional to the wheel speed is supplied to the electronic control unit 10.

Further, a sub-cylinder 70 is interposed in the main hydraulic pressure passage 8 between the hydraulic pressure limit switching device 20 and the wheel cylinders 51 and 52. A sub-hydraulic passage 9a branches from the main hydraulic passage 9 and a sub-cylinder 70 is connected to the branch. In the sub-cylinder 70, a piston 72 is slidably accommodated in a cylinder 71, and a first pressure chamber 74 and a second pressure chamber 75 are formed on both sides of the cylinder 71 via the piston 72. . A compression spring 73 is housed in the second pressure chamber 75, and when no hydraulic pressure is applied to the first and second pressure chambers 74 and 75, the second pressure chamber 75 has a maximum capacity (accordingly, The compression spring 73 urges the piston 72 to the left in FIG. 1 so that the first pressure chamber 74 has the minimum capacity.

An electromagnetic on-off valve 61 is interposed in the sub-hydraulic passage 9a connected to the first pressure chamber 74, and a check valve 62 is connected in parallel to the electromagnetic on-off valve 61. ing. The solenoid on-off valve 61 is a normally-closed two-port two-position solenoid valve that is closed when not in operation, and in the open position when in operation, the first pressure chamber 74 is connected to the regulator via the sub hydraulic passage 9a. Communicate with 3. Therefore, in the sub-cylinder 70, if the electromagnetic on-off valve 61 is in the open position, the first pressure chamber 7
4 is provided with a regulator hydraulic pressure (substantially equal to the master cylinder hydraulic pressure), and the second pressure chamber 75 is provided with a wheel cylinder hydraulic pressure, but both pressure chambers are hydraulically separated by a piston 72. I have. When the hydraulic pressure is not applied to the first and second pressure chambers 74 and 75,
The piston 72 is at a position where the capacity of the first pressure chamber 74 is minimized as shown in FIG.

When the solenoid on-off valve 61 is in the open position and the regulator pressure is applied to the first pressure chamber 74 via the on-off valve 61, the piston 72 moves in the direction of reducing the second pressure chamber 75. Since the brake fluid is driven, the brake fluid in the second pressure chamber 75 is discharged to the wheel cylinders 51 and 52 via the main hydraulic pressure passage 8 to increase the pressure. At this time, the wheel cylinder 5
The amount of brake fluid discharged to the first and second pressure chambers
Since the maximum capacity of the wheel cylinder 5 is limited,
There is no excessive supply of brake fluid to 1,52. Note that the regulator hydraulic pressure may be directly applied to the wheel cylinders 51 and 52 when the electromagnetic on-off valve 61 is in the open position without providing the sub cylinder 70.

Although omitted in the present embodiment,
Between the sub cylinder 70 and the wheel cylinders 51 and 52, and between the hydraulic pressure limit switching device 30 and the wheel cylinder 5
It is also possible to interpose a modulator composed of a plurality of electromagnetic valves between the electronic control units 3 and 54, and control the electronic control unit 10. According to this, not only the anti-skid control but also the traction control, the longitudinal braking force distribution control, the brake steering control, and the like can be performed by controlling the output hydraulic pressure of the regulator 3 by the modulator.

In the braking control device configured as described above, the hydraulic pump 41 is driven by the electric motor 42, and the power hydraulic pressure is accumulated in the accumulator 44. When the brake pedal 5 is depressed when each solenoid valve is in the state shown in FIG. 1, the master cylinder 2 outputs the master cylinder hydraulic pressure and the regulator 3 outputs the regulator hydraulic pressure. Then, a series of processes of the braking control is performed by the electronic control unit 10, and a program corresponding to the flowcharts of FIGS. 2 to 4 and the like is executed while the vehicle is traveling.

In FIG. 2, when it is determined in step 101 that an ignition switch (not shown) is turned on, the process proceeds to step 102, where an initial check is performed. Specifically, it is determined whether the condition for performing regenerative braking is satisfied based on the detection results of the state of the electric motor 11, the state of the transmission 12, and the state of the battery 13. For example, when driving at extremely low speeds, when the battery is fully charged, when the state of the battery indicates an increase in the battery internal pressure, when there is a failure, and when the battery is in the neutral shift position, it is determined that the condition for performing regenerative braking is not satisfied. , An alarm is given as appropriate.

If the start conditions are satisfied, step 103
It is determined whether the conditions for performing the high-speed hydraulic pressure control are satisfied or not, and if so, steps 104 and 1 are performed.
At step 05, the regenerative braking control and hydraulic pressure control peculiar to the high-speed running of the vehicle are performed according to a separate subroutine (not shown). In step 106, it is determined whether or not the condition for performing the hydraulic control at low speed is satisfied. If the condition is satisfied, the process proceeds to steps 107 and 108, and when the vehicle is running at low speed according to a separate subroutine (not shown). Specific regenerative braking control and hydraulic pressure control are performed, and if not satisfied, the routine proceeds to step 109 as it is. Thus, the process returns to step 103 and the above control is repeated until it is determined in step 109 that the ignition switch (not shown) is off.

FIG. 3 shows a process common to the regenerative braking control executed in steps 104 and 107 of FIG. 2. First, at step 201, the battery voltage Vb is detected, and at step 202, the brake switch is turned on. Is determined. If the brake switch 6 is on, step 203
The shift position of the transmission 12 is determined, and the drive position (D) or the motor brake position (B) is determined.
If so, the process proceeds to step 204. The motor brake position (B) is a shift position peculiar to an electric vehicle. In this position, the brake operation is not performed but the state is the same as that of the engine brake. In step 204, the regenerative braking torque is set according to the control mode during high-speed running or low-speed running. Subsequently, the routine proceeds to step 205, where it is determined whether or not the battery voltage Vb has exceeded a predetermined upper limit value Vbmax. Steps 202, 203,
When NO is determined in 205, the process returns to the main routine.

FIG. 4 shows the regenerative braking torque reduction control process executed in step 206 of FIG. 3. First, PI control is performed in step 301, and step 30 is performed.
At 2, the required value Tbv of the regenerative braking torque by the PI control is compared with the reference value Tbc. FIG. 5 shows the basic operation of the PI control performed in step 301. That is, in (A) showing a change in battery voltage,
A P term (proportional term) proportional to a deviation Vd between the battery voltage Vb and the upper limit value Vbmax, and an I term (integral term, which is plotted in FIG. , The control amount shown by the broken line in FIG.
The control is performed by subtracting this control amount from the regenerative braking torque shown in (C). Therefore, generally, as shown in FIG. 5C, the regenerative braking starts at the point a and the control for reducing the regenerative braking torque starts at the point b. Will return to value.

In step 302 of FIG. 4, the required value Tbv
When it is determined that the absolute value is equal to or greater than the reference value Tbc, the process proceeds to step 303 and thereafter. When the absolute value is less than the reference value Tbc, the process returns to the routine of FIG. In step 303, the previous required value Tbv _{(n-1 )} is compared with the current required value Tbv _(n) . The current request value Tbv _(n) is the previous request value Tbv
_When it is determined that the difference is smaller than _(n-1) (corresponding to the point h in FIG. 5C), the control amount (reduction amount) obtained at every predetermined cycle
Means that has changed from increasing to decreasing, the required value Tbv _(n) is stored in the memory in step 304. Then, the routine proceeds to step 305, where the required value Tbv _(n) is changed to the required value T of the regenerative braking torque in the regenerative braking operation thereafter.
Retained as bv. That is, control is performed as shown by a two-dot chain line in FIG. 5, and the regenerative braking torque is maintained at the minimum value.

FIG. 6 shows a change in the battery voltage, a change in the regenerative braking torque, a change in the master cylinder hydraulic pressure and a change in the wheel cylinder hydraulic pressure in the present embodiment. At the same time, the hydraulic brake enters a standby state (a state in which the brake pedal 6 is operated and the master cylinder hydraulic pressure and the regulator hydraulic pressure are output, but are not involved in applying the braking force to the wheels).
Then, when the regenerative braking torque reduction control is started at the point b, hydraulic braking by the regulator hydraulic pressure (via the sub cylinder 70) is performed to secure a braking force that compensates for this. Thereafter, in the above-described conventional device, the value of the regenerative braking torque returns to the original value at the point c as shown by the broken line in FIG. 6, whereas in the present embodiment, the value is shown by the solid line in FIG. Thus, the regenerative braking torque is maintained at the minimum value (h-point value). Thus, the braking force on the wheels is made uniform by the hydraulic braking torque after the introduction of the regulator hydraulic pressure and the regenerative braking torque, and the brake feeling is significantly improved as compared with the conventional device.

[0031]

The present invention has the following effects because it is configured as described above. That is, in the braking control device for an electric vehicle according to the present invention, when the voltage of the battery detected by the voltage detection means exceeds a predetermined upper limit value during the regenerative braking operation by the motor control means, the regeneration by the motor control means is performed. When the braking torque is reduced in a predetermined cycle, and the amount of reduction in each predetermined cycle changes from increasing to decreasing, the state of the reduction amount is maintained, and the amount of reduction in each predetermined cycle changes from increasing to decreasing. After that, the control is performed so that the hydraulic braking by the hydraulic control means is continued until the vehicle stops, so that the braking operation can be smoothly performed until the vehicle stops, and a good brake feeling is secured. be able to.

Further, in the case of the structure described in claim 2, the hydraulic braking can be performed quickly and smoothly by the output hydraulic pressure of the dynamic hydraulic pressure output means.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a braking control device for an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a brake control process according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a process of regenerative braking control according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating a process of controlling regenerative braking torque reduction according to an embodiment of the present invention.

FIG. 5 shows a voltage change of a battery according to an embodiment of the present invention;
4 is a graph showing changes in a control amount and regenerative braking torque by PI control.

FIG. 6 shows a voltage change of a battery according to an embodiment of the present invention;
5 is a graph showing a change in regenerative braking torque, a change in master cylinder hydraulic pressure and a change in wheel cylinder hydraulic pressure.

FIG. 7 is a graph showing a relationship between a master cylinder hydraulic pressure and a wheel cylinder hydraulic pressure by first and second relief valves, a proportioning valve, and an electromagnetic on-off valve according to an embodiment of the present invention.

[Explanation of symbols]

 2 Master cylinder, 3 Regulator 5 Brake pedal 10 Electronic control unit 11 Electric motor 20, 30 Fluid pressure limit switching device 21 First relief valve 22 Electromagnetic on-off valve 23, 33 Proportioning valve 24, 25 Pressure sensor 26 Second relief Valve 27 Solenoid on-off valve 32 Solenoid on-off valve 40 Auxiliary hydraulic pressure source 51, 52, 53, 54 Wheel cylinder 61 Solenoid on-off valve FR, FL, RR, RL Wheel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shingo Urababa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Harumi Ohori 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (2)

[Claims] 1. An electric motor connected to wheels of a vehicle, a battery mounted on the vehicle, and the battery is used as a power source to rotationally drive the electric motor to apply a driving force to the wheels and to regenerate the electric motor. A motor control means for applying a braking force to the wheel by braking; and a braking force to the wheel by hydraulic braking for supplying a brake hydraulic pressure to a wheel cylinder mounted on the wheel in accordance with an operation of a brake operating member. A braking control device for an electric vehicle, comprising: a hydraulic pressure control unit; a voltage detection unit configured to detect a voltage of the battery; and a voltage of the battery detected by the voltage detection unit during a regenerative braking operation by the motor control unit. Means for reducing a regenerative braking torque by the motor control means at a predetermined cycle when the value exceeds a predetermined upper limit value; And a holding unit for holding the state of the reduction amount when the reduction amount in each period has changed from increasing to decreasing, and the reduction amount in the predetermined cycle in which the reducing unit reduces has changed from increasing to decreasing. A brake control device for an electric vehicle, wherein control is performed such that hydraulic braking by the hydraulic pressure control means is continued until the vehicle stops. 2. The hydraulic pressure control means according to claim 1, wherein said hydraulic pressure control means boosts brake fluid in said reservoir in response to operation of said brake operating member and outputs static hydraulic pressure. An auxiliary hydraulic pressure source that boosts and outputs power hydraulic pressure regardless of the operation of the brake operating member; and adjusts the output power hydraulic pressure of the auxiliary hydraulic pressure source in accordance with the operation of the brake operating member to adjust the dynamic hydraulic pressure. A dynamic hydraulic pressure output means for outputting pressure, and performs hydraulic braking by supplying output hydraulic pressure of the dynamic hydraulic pressure output means to a wheel cylinder mounted on a wheel connected to the electric motor; Control is performed so that the hydraulic braking by the output hydraulic pressure of the dynamic hydraulic pressure output means is continued until the vehicle stops even after the reduction amount of the predetermined period in which the reduction means reduces decreases from increasing to decreasing. 2. The method according to claim 1, wherein On-board electric vehicle braking control device.